CA1075799A - Erasable visual image display device - Google Patents
Erasable visual image display deviceInfo
- Publication number
- CA1075799A CA1075799A CA277,283A CA277283A CA1075799A CA 1075799 A CA1075799 A CA 1075799A CA 277283 A CA277283 A CA 277283A CA 1075799 A CA1075799 A CA 1075799A
- Authority
- CA
- Canada
- Prior art keywords
- electrode
- electrodes
- permselective membrane
- display device
- image display
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000000007 visual effect Effects 0.000 title claims abstract description 9
- 239000012528 membrane Substances 0.000 claims abstract description 34
- 150000001768 cations Chemical class 0.000 claims abstract description 22
- 150000001450 anions Chemical class 0.000 claims abstract description 19
- 230000002441 reversible effect Effects 0.000 claims abstract description 8
- FAAXSAZENACQBT-UHFFFAOYSA-N benzene-1,2,4,5-tetracarbonitrile Chemical compound N#CC1=CC(C#N)=C(C#N)C=C1C#N FAAXSAZENACQBT-UHFFFAOYSA-N 0.000 claims abstract description 3
- XQZYPMVTSDWCCE-UHFFFAOYSA-N phthalonitrile Chemical compound N#CC1=CC=CC=C1C#N XQZYPMVTSDWCCE-UHFFFAOYSA-N 0.000 claims description 3
- 238000001429 visible spectrum Methods 0.000 claims description 3
- 150000002825 nitriles Chemical class 0.000 claims description 2
- 230000005684 electric field Effects 0.000 claims 2
- 150000005837 radical ions Chemical class 0.000 claims 2
- 239000003960 organic solvent Substances 0.000 claims 1
- MCGBIXXDQFWVDW-UHFFFAOYSA-N 4,5-dihydro-1h-pyrazole Chemical compound C1CC=NN1 MCGBIXXDQFWVDW-UHFFFAOYSA-N 0.000 abstract description 2
- 239000000463 material Substances 0.000 description 17
- 150000002500 ions Chemical class 0.000 description 7
- 239000002904 solvent Substances 0.000 description 6
- 230000007935 neutral effect Effects 0.000 description 5
- 238000013459 approach Methods 0.000 description 4
- 230000003287 optical effect Effects 0.000 description 4
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 description 3
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000005855 radiation Effects 0.000 description 3
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 2
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 2
- 230000003213 activating effect Effects 0.000 description 2
- 230000005518 electrochemistry Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000005192 partition Methods 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 125000006850 spacer group Chemical group 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- CMSGUKVDXXTJDQ-UHFFFAOYSA-N 4-(2-naphthalen-1-ylethylamino)-4-oxobutanoic acid Chemical compound C1=CC=C2C(CCNC(=O)CCC(=O)O)=CC=CC2=C1 CMSGUKVDXXTJDQ-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 229920002125 Sokalan® Polymers 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 238000003491 array Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- -1 diethylaminostyryl Chemical group 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000003456 ion exchange resin Substances 0.000 description 1
- 229920003303 ion-exchange polymer Polymers 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- KRTSDMXIXPKRQR-AATRIKPKSA-N monocrotophos Chemical compound CNC(=O)\C=C(/C)OP(=O)(OC)OC KRTSDMXIXPKRQR-AATRIKPKSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000002085 persistent effect Effects 0.000 description 1
- WSDQIHATCCOMLH-UHFFFAOYSA-N phenyl n-(3,5-dichlorophenyl)carbamate Chemical compound ClC1=CC(Cl)=CC(NC(=O)OC=2C=CC=CC=2)=C1 WSDQIHATCCOMLH-UHFFFAOYSA-N 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920000172 poly(styrenesulfonic acid) Polymers 0.000 description 1
- 239000004584 polyacrylic acid Substances 0.000 description 1
- 229920000867 polyelectrolyte Polymers 0.000 description 1
- 229940005642 polystyrene sulfonic acid Drugs 0.000 description 1
- 229920002717 polyvinylpyridine Polymers 0.000 description 1
- DNXIASIHZYFFRO-UHFFFAOYSA-N pyrazoline Chemical compound C1CN=NC1 DNXIASIHZYFFRO-UHFFFAOYSA-N 0.000 description 1
- 150000003219 pyrazolines Chemical class 0.000 description 1
- 150000005838 radical anions Chemical class 0.000 description 1
- 150000005839 radical cations Chemical class 0.000 description 1
- 150000003254 radicals Chemical class 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K9/00—Tenebrescent materials, i.e. materials for which the range of wavelengths for energy absorption is changed as a result of excitation by some form of energy
- C09K9/02—Organic tenebrescent materials
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/15—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on an electrochromic effect
- G02F1/1514—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on an electrochromic effect characterised by the electrochromic material, e.g. by the electrodeposited material
- G02F1/1516—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on an electrochromic effect characterised by the electrochromic material, e.g. by the electrodeposited material comprising organic material
Landscapes
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Nonlinear Science (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Devices For Indicating Variable Information By Combining Individual Elements (AREA)
- Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)
Abstract
ERASABLE VISUAL IMAGE DISPLAY DEVICE
ABSTRACT OF THE DISCLOSURE
An erasable visual image display device contains a pair of conductive electrodes in spaced relationship. One electrode has a cation permselective membrane thereon and the other electrode has an anion permselective membrane thereon. Positioned between the two membranes is a recording medium having the properties of being both photoionizable and capable of electrochemically producing colored species. The medium contains an electrochemically reversible acceptor molecule, for example, 1, 2, 4, 5 tetracyanobenzene and an electrochemically reversible donor molecule, for example, l-phenyl-3 diethylaminostyrl -5-diethylaminophenyl .DELTA.2 pyrazoline.
ABSTRACT OF THE DISCLOSURE
An erasable visual image display device contains a pair of conductive electrodes in spaced relationship. One electrode has a cation permselective membrane thereon and the other electrode has an anion permselective membrane thereon. Positioned between the two membranes is a recording medium having the properties of being both photoionizable and capable of electrochemically producing colored species. The medium contains an electrochemically reversible acceptor molecule, for example, 1, 2, 4, 5 tetracyanobenzene and an electrochemically reversible donor molecule, for example, l-phenyl-3 diethylaminostyrl -5-diethylaminophenyl .DELTA.2 pyrazoline.
Description
14 Field of the Invention This invention relates to optically addressable display devices and 16 more particularly to devices that can be erased.
17 Brief Description of Prior Art 18 Many different approaches to direct ~iew display devices are known.
19 One approach is to use a photochromic material in a display device to produce a direct view image. However, these devices are of relatively 21 low optical sensitivity and require the use of thermal or in some cases 22 visible radiation to erase the image and allow subsequent reuse.
23 The prior art also teaches the use of structural electrode arrays 24 to produce electrochromic images in the form of characters and images.
There is a one-to-one correspondence between the electrodes or activated 26 electrode segment and the resulting image. This in general reduces the 27 versatility of the device due to preconfiguration requirements and also 28 presents certain difficulties in addressing and driving the display.
29 Another approach is to use a device with a photoconductive material overlaying an electrochromic material. The optical image reduces the ~k . - : .. . :
.. . . -. . - : : . , :: - : : .
. . : , - . ,, : . : . -,, . -. , . .
. .
~ ..
: : - . . : . , .
107579~
1 resistance of the photoconductive material in the exposed area so that
17 Brief Description of Prior Art 18 Many different approaches to direct ~iew display devices are known.
19 One approach is to use a photochromic material in a display device to produce a direct view image. However, these devices are of relatively 21 low optical sensitivity and require the use of thermal or in some cases 22 visible radiation to erase the image and allow subsequent reuse.
23 The prior art also teaches the use of structural electrode arrays 24 to produce electrochromic images in the form of characters and images.
There is a one-to-one correspondence between the electrodes or activated 26 electrode segment and the resulting image. This in general reduces the 27 versatility of the device due to preconfiguration requirements and also 28 presents certain difficulties in addressing and driving the display.
29 Another approach is to use a device with a photoconductive material overlaying an electrochromic material. The optical image reduces the ~k . - : .. . :
.. . . -. . - : : . , :: - : : .
. . : , - . ,, : . : . -,, . -. , . .
. .
~ ..
: : - . . : . , .
107579~
1 resistance of the photoconductive material in the exposed area so that
2 the corresponding area of the electrochromic material is energized by a
3 voltaqe across the cell. This configuration solves the electrode pro-
4 blem of electrochromic devices but requires a more complex structure due to the layered structure. The materials must be selected for compat-6 ibility with all the other materials. Furthermore, the exposure and 7 application of the voltage must be simultaneous unless a persistent .~ 8 photoconductor is used. - -9 Still another approach is described in U.S. patent no. 4,126,456 issued November 21, 1978, and assigned to the assignee of the present 11 invention. The direct view display device described in that patent 12 includes a pair of conductive electrodes in spaced relationship and a 3 suitable recording medium occupying the space between the electrodes.
4 The recording medium exhibits the properties of being photoionizable and capable of electrochemically producing colored species. The image is 16 produced by exposing the medium to an optical pattern of activating 7 radiation of an intensity suitable to produce a latent image of the 18 pattern and then applying a low voltage of a first polarity across the 19 electrodes to produce a very dense image corresponding to the pattern.
Ths image can be erased by applying a low voltage of opposite polarity 21 across the electrodes and the display device can then be reused. These 22 devi¢es are suitable for many applications. In some instances, however, 23 it is desirable to improve the erasability characteristics.
24 The use of permselective membranes in electrochromic devices are -disclosed in the U.S. patent 3,453,038 issued July 1, 1969, to Kissa et 26 al, and in U.S. Patent 3,303,488 issued February 7, 1967 to Anderson.
27 Kissa et al discloses a single transparent permselective membrane which ' 28 serves as a partition to divide the electrochromic cell into an anode 29 compartment and a cathode compartment. This partition further segre- ~
30 gates the color change reaction from the cell balancing reaction. : --,'`, ~
. ~ : ' ' ' . , . ' ' ' ' ' :~ . ' ' '" :
S7~
1 The permselective membrane is permeable to electrolyte ions~ that is, 2 ions formed in an ac~ueous solution. The membrane is not permeable to 3 the redox species, that is, the species that form the color.
It is a primary ob~ect of this invention to provide an improved 6 visual image display device.
7 It is another object of this invention to provide a visual image 8 display device adapted to the easily erased and reused.
9 These and other objects are accomplished by an erasable visual image display device having two conductive electrodes in spaced rela-11 tionship. On one electrode is an anion permselective membrane and on 12 the other electrode is a cation permselective membrane. Positioned 13 between the membranes is a normally light transmitting recording medium14 which is both photoionizable and capable of electrochemically producingcolored species. The medium may advantageously contain a solvent, an 16 electrochemically reversible donor molecule, for example, 1 phenyl-3 17 diethylaminostyryl 5-diethylamino ~ pyrazoline (hereinafter referred to18 as DEASP), and electrochemically reversible acceptor molecule, for 19 example, 1, 2, 4, 5 tetracyanobenzene. The image is produced by ex-posing the medium to an optical pattern of activating radiation of an 21 intensity suitable to provide a latent image of the pattern and then 22 applying a low voltage of a first polarity across the electrodes to 23 produce a very dense image corresponding to the pattern. When DEASP is 24 used in the medium as the donor molecule, the stable radical DEAspt cation is formed and is responsible for the colored image. The image 26 can be erased by applying a low voltage of opposite polarity across the 27 electrodes. Applying the opposite polarity voltage causes the donor 28 radical cation, for example DEASP~, to pass through the cation perm-29 selective membrane and be discharged at the electrode to form a neutral molecule. Similarly, the acceptor radical anion passes through the 31 anion permselective membrane and is discharged at the electrode to form 32 a neutral molecule.
SA975069 ~3-,,~ .
.
. .. , , ~
' 10~5"~99 1 The display device can then be reused.
2 Other objects of this invention will be apparent from the following 3 detailed description, reference being made to the accompany drawing 4 wherein a specific embodiment of the invention is shown.
Brief Description of the Drawing 6 The drawing is a cross-sectional view of the display device embodying 7 the invention.
Description of the Illustrative Embodiment 9 The visual image display device 10 contains transparent electrodes 12 and 14 on substrates 16 and 18, respectively. The transparent electrodes 11 12 and 14 are typically NESA*material, that is, SnO, InO and mixtures 12 thereof or it may be a thin layer of gold, platinum or equivalent materials.
13 The substrates 16 and 18 are typically glass although equivalent transparent 14 materials may be used.
In accordance with this invention transparent electrode 12 has a 16 cation permselective membrane 20 thereon and transparent electrode 14 ~ -17 has an anion permselective membrane 22 thereon. The cation permselective 18 membrane 20 will prevent the discharge of the anion on electrode 12 1~ while the anion permselective membrane 22 will prevent discharge of the cation on electrode 14. These membranes are made of materials commonly 21 known as ion-exchange resins and their permselective properties with 22 respect to ions are applied in this invention. The most suitable type 23 of such materials for this application are the polyelectrolytes which 24 are polymeric materials whose monomeric units possess ionizable groups.
These groups are usually acidic (polyacid) or basic ~polybase) depending 26 on whether they are to be cation permselective or anion permselective.
27 Examples of polyacids are polyacrylic acid and polystyrenesulfonic acid.
28 Polyvinylamine and polyvinyl pyridine are examples of polybases. These 29 materials and molecular weights are chosen so that the membranes do not dissolve in the solution but are permeable to the solvent molecules and *Irade Mark SA975069 -4_ .~ . .
~075799 1 the appropriate neutral donor and accepto'r molecules besides being 2 chemically inert with respect to them.
3 The spacing between the membrane 20 and 22 is maintained by a 4 suitable spacer member 24 Positioned within the space formed by spacer members 24 and membranes 20 and 22 is recording material 26. The thickness 6 of the cell is normally in the range of 50 to lO0 microns, and this 7 thickness is chosen on the basis of the desired response time, resolution 8 and other characteristics chosen for a specific display device.
9 The recording medium 26 exhibits the properties of being both photoionizable and capable of electrochemically producing colored species.
11 In accordance with this invention the recording medium 26 includes the 12 donor molecule able to reversibly generate stable cations through anodic 13 oxidation and acceptor molecules which can be reversibly generated 14 stable anions through cathodic reduction. A number of suitable materials for providing reversible donor molecules are the triayrl pyrazolines and 16 spiropyrans of such as are disclosed in the aforementioned U.S.
17 patent 4,126,456. A preferred donor molecule is formed with l-phenyl-18 3-diethylaminostyrl -5-diethylaminophenyl _ ~2_ pyrazoline. Compounds 19 which provide a suitable acceptor molecule are l, 2, 4, 5 tetracyanobenzene, l, 2 dicyanoben~ene; l, 4 dicyanobenzene and furmaric nitrile.
21 Suitable solvents for use in the recording medium 26 are hallogenated 22 hydrocarbon solvents, non-acqueous solvents such as acetonitrile and 23 tetrahydrofuran. Preferred solvents are chloroform, l, 2, dichloromethane 24 and mixtures thereof.
The display cell lO is fully transparent under ambient light.
26 However, when a region of a cell is exposed by light distribution as 27 shown in the drawing to the light of the wavelength to which the material 28 26 is sensitive with an energy density of about lO to 50 micron per 29 centimeter squared, a latent image is produced in the irradiated region.
f 30 Image enhancement comprises a conversion of the latent imagc into a .,.; ~
"' .
107579g 1 high density and high contrast visible image, and the enhancement is 2 achieved by the momentary application of a potential positive on the 3 electrode with the cation permselective membrane ~o the displaced cell 4 which results in the subsequent production of colored species in those areas that have been exposed to light. In the embodiment shown in the 6 drawing, the enhancement is accomplished by the application of potential 7 of about 2 to 20 volts from voltage source 28 by switch 30 to the device 8 so that the coloration in the same region is intensified. The intensifi-g cation is proportional to the applied voltage and the duration of its 10 application. .
11 The latent image that is formed byIthe photoionization process is 12 thought to consist of a contrast of ion densities, i.e., a high concentration 13 of ions in the illuminated regions in contrast to a low concentration in 14 the non-illumlnated regions. When the enhancing voltage is applied the ions separate to their respective electrodes but are not dischared due 16 to the presence of the permselective membrane. For example, the DEASP
17 cations form a layer next to the anion permselective membrane and the 18 tetracyanobenzene anions form a layer next to the cation permselective 19 membrane. Thus, an effective double layer is formed allowing electro-chemistry to take place in the illuminated area whereas in the non-21 illuminated area the ion density is too low for electrochemistry to take 22 place.
23 During the application of the potential the donor molecule is 24 oxidized at the anode to form the cation while the acceptor molecule is reduced at the cathode to form the anion. Either the cation or the 26 anion or both are chose to absorb light in the visible spectrum to form the 27 desired color. In the preferred embodiment the color is formed by the 28 donor molecule.
29 The display device is erased by reversing the potential on the cell by switch 30 which causes the colored species to be bleached. In accordance ., -~ SA975069 -6-':
~0`^~5799 1 with this invention the presence of the cation permselective membrane on 2 one electrode and the anion permselective membrane on the other electrodes 3 insures that both the cation and the anion will be discharged at the 4 appropriate electrode thereby insuring the successful erasure of the device. For example, the DEASP cations which were in a layer next to 6 the anion permselective membrane migrate to and penetrate through the 7 cation permselective membrane to the electrode where they are discharged 8 to form the original neutral donor molecules suitable for reuse. Similarly 9 the tetracyanobenzene anions which were in a layer next to the cation permselective membrane migrate to and penetrate through the anion permselective 11 membrane to the electrode where they are tischarged to form the original 12 neutral acceptor molecules suitable for reuse. It is also necessary, of 13 course, to have donor and acceptor molecules which are electrochemically 14 reversible.
Although a preferred embodiment of this invention has been described, 16 it is understood that numerous variations may be made in accordance with 17 the principles of this invention.
: ' .
.
4 The recording medium exhibits the properties of being photoionizable and capable of electrochemically producing colored species. The image is 16 produced by exposing the medium to an optical pattern of activating 7 radiation of an intensity suitable to produce a latent image of the 18 pattern and then applying a low voltage of a first polarity across the 19 electrodes to produce a very dense image corresponding to the pattern.
Ths image can be erased by applying a low voltage of opposite polarity 21 across the electrodes and the display device can then be reused. These 22 devi¢es are suitable for many applications. In some instances, however, 23 it is desirable to improve the erasability characteristics.
24 The use of permselective membranes in electrochromic devices are -disclosed in the U.S. patent 3,453,038 issued July 1, 1969, to Kissa et 26 al, and in U.S. Patent 3,303,488 issued February 7, 1967 to Anderson.
27 Kissa et al discloses a single transparent permselective membrane which ' 28 serves as a partition to divide the electrochromic cell into an anode 29 compartment and a cathode compartment. This partition further segre- ~
30 gates the color change reaction from the cell balancing reaction. : --,'`, ~
. ~ : ' ' ' . , . ' ' ' ' ' :~ . ' ' '" :
S7~
1 The permselective membrane is permeable to electrolyte ions~ that is, 2 ions formed in an ac~ueous solution. The membrane is not permeable to 3 the redox species, that is, the species that form the color.
It is a primary ob~ect of this invention to provide an improved 6 visual image display device.
7 It is another object of this invention to provide a visual image 8 display device adapted to the easily erased and reused.
9 These and other objects are accomplished by an erasable visual image display device having two conductive electrodes in spaced rela-11 tionship. On one electrode is an anion permselective membrane and on 12 the other electrode is a cation permselective membrane. Positioned 13 between the membranes is a normally light transmitting recording medium14 which is both photoionizable and capable of electrochemically producingcolored species. The medium may advantageously contain a solvent, an 16 electrochemically reversible donor molecule, for example, 1 phenyl-3 17 diethylaminostyryl 5-diethylamino ~ pyrazoline (hereinafter referred to18 as DEASP), and electrochemically reversible acceptor molecule, for 19 example, 1, 2, 4, 5 tetracyanobenzene. The image is produced by ex-posing the medium to an optical pattern of activating radiation of an 21 intensity suitable to provide a latent image of the pattern and then 22 applying a low voltage of a first polarity across the electrodes to 23 produce a very dense image corresponding to the pattern. When DEASP is 24 used in the medium as the donor molecule, the stable radical DEAspt cation is formed and is responsible for the colored image. The image 26 can be erased by applying a low voltage of opposite polarity across the 27 electrodes. Applying the opposite polarity voltage causes the donor 28 radical cation, for example DEASP~, to pass through the cation perm-29 selective membrane and be discharged at the electrode to form a neutral molecule. Similarly, the acceptor radical anion passes through the 31 anion permselective membrane and is discharged at the electrode to form 32 a neutral molecule.
SA975069 ~3-,,~ .
.
. .. , , ~
' 10~5"~99 1 The display device can then be reused.
2 Other objects of this invention will be apparent from the following 3 detailed description, reference being made to the accompany drawing 4 wherein a specific embodiment of the invention is shown.
Brief Description of the Drawing 6 The drawing is a cross-sectional view of the display device embodying 7 the invention.
Description of the Illustrative Embodiment 9 The visual image display device 10 contains transparent electrodes 12 and 14 on substrates 16 and 18, respectively. The transparent electrodes 11 12 and 14 are typically NESA*material, that is, SnO, InO and mixtures 12 thereof or it may be a thin layer of gold, platinum or equivalent materials.
13 The substrates 16 and 18 are typically glass although equivalent transparent 14 materials may be used.
In accordance with this invention transparent electrode 12 has a 16 cation permselective membrane 20 thereon and transparent electrode 14 ~ -17 has an anion permselective membrane 22 thereon. The cation permselective 18 membrane 20 will prevent the discharge of the anion on electrode 12 1~ while the anion permselective membrane 22 will prevent discharge of the cation on electrode 14. These membranes are made of materials commonly 21 known as ion-exchange resins and their permselective properties with 22 respect to ions are applied in this invention. The most suitable type 23 of such materials for this application are the polyelectrolytes which 24 are polymeric materials whose monomeric units possess ionizable groups.
These groups are usually acidic (polyacid) or basic ~polybase) depending 26 on whether they are to be cation permselective or anion permselective.
27 Examples of polyacids are polyacrylic acid and polystyrenesulfonic acid.
28 Polyvinylamine and polyvinyl pyridine are examples of polybases. These 29 materials and molecular weights are chosen so that the membranes do not dissolve in the solution but are permeable to the solvent molecules and *Irade Mark SA975069 -4_ .~ . .
~075799 1 the appropriate neutral donor and accepto'r molecules besides being 2 chemically inert with respect to them.
3 The spacing between the membrane 20 and 22 is maintained by a 4 suitable spacer member 24 Positioned within the space formed by spacer members 24 and membranes 20 and 22 is recording material 26. The thickness 6 of the cell is normally in the range of 50 to lO0 microns, and this 7 thickness is chosen on the basis of the desired response time, resolution 8 and other characteristics chosen for a specific display device.
9 The recording medium 26 exhibits the properties of being both photoionizable and capable of electrochemically producing colored species.
11 In accordance with this invention the recording medium 26 includes the 12 donor molecule able to reversibly generate stable cations through anodic 13 oxidation and acceptor molecules which can be reversibly generated 14 stable anions through cathodic reduction. A number of suitable materials for providing reversible donor molecules are the triayrl pyrazolines and 16 spiropyrans of such as are disclosed in the aforementioned U.S.
17 patent 4,126,456. A preferred donor molecule is formed with l-phenyl-18 3-diethylaminostyrl -5-diethylaminophenyl _ ~2_ pyrazoline. Compounds 19 which provide a suitable acceptor molecule are l, 2, 4, 5 tetracyanobenzene, l, 2 dicyanoben~ene; l, 4 dicyanobenzene and furmaric nitrile.
21 Suitable solvents for use in the recording medium 26 are hallogenated 22 hydrocarbon solvents, non-acqueous solvents such as acetonitrile and 23 tetrahydrofuran. Preferred solvents are chloroform, l, 2, dichloromethane 24 and mixtures thereof.
The display cell lO is fully transparent under ambient light.
26 However, when a region of a cell is exposed by light distribution as 27 shown in the drawing to the light of the wavelength to which the material 28 26 is sensitive with an energy density of about lO to 50 micron per 29 centimeter squared, a latent image is produced in the irradiated region.
f 30 Image enhancement comprises a conversion of the latent imagc into a .,.; ~
"' .
107579g 1 high density and high contrast visible image, and the enhancement is 2 achieved by the momentary application of a potential positive on the 3 electrode with the cation permselective membrane ~o the displaced cell 4 which results in the subsequent production of colored species in those areas that have been exposed to light. In the embodiment shown in the 6 drawing, the enhancement is accomplished by the application of potential 7 of about 2 to 20 volts from voltage source 28 by switch 30 to the device 8 so that the coloration in the same region is intensified. The intensifi-g cation is proportional to the applied voltage and the duration of its 10 application. .
11 The latent image that is formed byIthe photoionization process is 12 thought to consist of a contrast of ion densities, i.e., a high concentration 13 of ions in the illuminated regions in contrast to a low concentration in 14 the non-illumlnated regions. When the enhancing voltage is applied the ions separate to their respective electrodes but are not dischared due 16 to the presence of the permselective membrane. For example, the DEASP
17 cations form a layer next to the anion permselective membrane and the 18 tetracyanobenzene anions form a layer next to the cation permselective 19 membrane. Thus, an effective double layer is formed allowing electro-chemistry to take place in the illuminated area whereas in the non-21 illuminated area the ion density is too low for electrochemistry to take 22 place.
23 During the application of the potential the donor molecule is 24 oxidized at the anode to form the cation while the acceptor molecule is reduced at the cathode to form the anion. Either the cation or the 26 anion or both are chose to absorb light in the visible spectrum to form the 27 desired color. In the preferred embodiment the color is formed by the 28 donor molecule.
29 The display device is erased by reversing the potential on the cell by switch 30 which causes the colored species to be bleached. In accordance ., -~ SA975069 -6-':
~0`^~5799 1 with this invention the presence of the cation permselective membrane on 2 one electrode and the anion permselective membrane on the other electrodes 3 insures that both the cation and the anion will be discharged at the 4 appropriate electrode thereby insuring the successful erasure of the device. For example, the DEASP cations which were in a layer next to 6 the anion permselective membrane migrate to and penetrate through the 7 cation permselective membrane to the electrode where they are discharged 8 to form the original neutral donor molecules suitable for reuse. Similarly 9 the tetracyanobenzene anions which were in a layer next to the cation permselective membrane migrate to and penetrate through the anion permselective 11 membrane to the electrode where they are tischarged to form the original 12 neutral acceptor molecules suitable for reuse. It is also necessary, of 13 course, to have donor and acceptor molecules which are electrochemically 14 reversible.
Although a preferred embodiment of this invention has been described, 16 it is understood that numerous variations may be made in accordance with 17 the principles of this invention.
: ' .
.
Claims (9)
1. A visual image display device comprising:
a first and a second conductive electrode in spaced-relationship;
a cation permselective membrane on said first electrode, an anion permselective membrane on said second electrode, a voltage source and means for selectively applying this voltage between the electrodes to produce an electric field; and a normally light transmitting recording medium occupying the space between said electrodes, said medium having the properties of being both photo-ionizable and capable of electrochemically producing colored species.
a first and a second conductive electrode in spaced-relationship;
a cation permselective membrane on said first electrode, an anion permselective membrane on said second electrode, a voltage source and means for selectively applying this voltage between the electrodes to produce an electric field; and a normally light transmitting recording medium occupying the space between said electrodes, said medium having the properties of being both photo-ionizable and capable of electrochemically producing colored species.
2. A device as described in claim 1 wherein said medium contains an organic solvent.
3. A device as described in claim 1 wherein said first and said second electrodes are semitransparent.
4. A visual image display device comprising:
a first and a second conductive electrode in spaced-relationship;
a cation permselective membrane on said first electrode, an anion permselective membrane on said second electrode, a voltage source and means for selectively applying this voltage between the electrodes to produce an electric field; and a normally light transmitting recording medium occupying the space between said electrodes, said medium having the properties of being both photo-ionizable and capable of electrochemically producing colored species; said medium contains an electrochemically reversible donor molecule and an electrochemically reversible acceptor molecule.
a first and a second conductive electrode in spaced-relationship;
a cation permselective membrane on said first electrode, an anion permselective membrane on said second electrode, a voltage source and means for selectively applying this voltage between the electrodes to produce an electric field; and a normally light transmitting recording medium occupying the space between said electrodes, said medium having the properties of being both photo-ionizable and capable of electrochemically producing colored species; said medium contains an electrochemically reversible donor molecule and an electrochemically reversible acceptor molecule.
5. A device as described in claim 4 wherein said donor molecule forms a radical ion adapted to absorb light in the visible spectrum to form the desired color.
6. A device as described in claim 4 wherein said acceptor molecule forms a radical ion adapted to absorb light in the visible spectrum to form the desired color.
7. A device as described in claim 4 wherein said acceptor molecule is taken from the group consisting of:
1, 2, 4, 5 tetracyanobenzene, 1, 2 dicyanobenzene; 1, 4, dicyanobenzene and furmaric nitrile.
1, 2, 4, 5 tetracyanobenzene, 1, 2 dicyanobenzene; 1, 4, dicyanobenzene and furmaric nitrile.
8. A device as described in claim 4 wherein said donor molecule is taken from the group consisting of triaryl - .DELTA.2 - pyrazoline and spiropyrans.
9. A device as described in claim 4 wherein said donor molecule is 1-phenyl-3-diethylaminostyrl-5-diethylaminophenyl - .DELTA.2 - pyrazoline.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/686,974 US4033673A (en) | 1976-05-17 | 1976-05-17 | Erasable visual image display device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1075799A true CA1075799A (en) | 1980-04-15 |
Family
ID=24758512
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA277,283A Expired CA1075799A (en) | 1976-05-17 | 1977-04-29 | Erasable visual image display device |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4033673A (en) |
| JP (1) | JPS52140352A (en) |
| CA (1) | CA1075799A (en) |
| DE (1) | DE2721600A1 (en) |
| FR (1) | FR2352363A1 (en) |
| GB (1) | GB1535684A (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4093358A (en) * | 1976-12-27 | 1978-06-06 | International Business Machines Corporation | High efficiency electrochromic display device |
| US4120568A (en) * | 1977-01-12 | 1978-10-17 | Optel Corporation | Electrochromic cell with protective overcoat layer |
| US4142783A (en) * | 1977-05-31 | 1979-03-06 | International Business Machines Corporation | Reversible electrochromic display device having memory |
| JPS58193804A (en) * | 1982-05-08 | 1983-11-11 | Okura Yusoki Co Ltd | Elevator |
| JPS597982A (en) * | 1982-07-07 | 1984-01-17 | Canon Inc | image display device |
| US4636787A (en) * | 1982-07-19 | 1987-01-13 | Canon Kabushiki Kaisha | Image display apparatus |
| US4599614A (en) * | 1983-09-13 | 1986-07-08 | Sumx Corporation | Photoelectrochromic display |
| JPS61138925A (en) * | 1984-12-12 | 1986-06-26 | Tokuyama Soda Co Ltd | Electrochromic display element |
| US4871236A (en) * | 1985-09-18 | 1989-10-03 | Kabushiki Kaisha Toshiba | Organic thin film display element |
| US4789965A (en) * | 1986-10-31 | 1988-12-06 | The University Of Utah | Methods and compositions for recording optical information employing molecular pseudorotation |
| JPS6433536A (en) * | 1987-07-29 | 1989-02-03 | Sony Corp | Electrochromic display device |
| US5473340A (en) * | 1990-09-27 | 1995-12-05 | The United States Of America As Represented By The Secretary Of The Navy | Apparatus for displaying a multi-color pattern |
| US5260606A (en) * | 1992-01-31 | 1993-11-09 | Litton Systems Canada Limited | High efficiency squarewave voltage driver |
| JP2005522870A (en) * | 2002-04-05 | 2005-07-28 | パワーザイム，インコーポレイテッド | Photodetector |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3453038A (en) * | 1966-06-15 | 1969-07-01 | Du Pont | Compartmented electrochromic device |
| US3589896A (en) * | 1968-05-27 | 1971-06-29 | Us Air Force | Electro-optical article employing electrochromic and photoconductive materials |
| US3840288A (en) * | 1973-07-30 | 1974-10-08 | Optel Corp | Electrochromic display having electro-catalyst |
| JPS50141328A (en) * | 1974-01-12 | 1975-11-13 |
-
1976
- 1976-05-17 US US05/686,974 patent/US4033673A/en not_active Expired - Lifetime
-
1977
- 1977-04-05 FR FR7711169A patent/FR2352363A1/en active Granted
- 1977-04-19 GB GB16289/77A patent/GB1535684A/en not_active Expired
- 1977-04-22 JP JP4597977A patent/JPS52140352A/en active Granted
- 1977-04-29 CA CA277,283A patent/CA1075799A/en not_active Expired
- 1977-05-13 DE DE19772721600 patent/DE2721600A1/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE2721600A1 (en) | 1977-11-24 |
| US4033673A (en) | 1977-07-05 |
| FR2352363B1 (en) | 1980-03-28 |
| JPS52140352A (en) | 1977-11-22 |
| JPS5725810B2 (en) | 1982-06-01 |
| GB1535684A (en) | 1978-12-13 |
| FR2352363A1 (en) | 1977-12-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1075799A (en) | Erasable visual image display device | |
| US4129861A (en) | Multiplex addressing of electrochromic displays | |
| US4810067A (en) | Electrochromic device and method of making an electrochromic layer therefor | |
| US4335938A (en) | Electrochromic cells with improved electrolyte system | |
| US4749260A (en) | Variable color transparent panels | |
| US4004849A (en) | Display apparatus and process | |
| CA1166731A (en) | Electrochromic display device | |
| US4586792A (en) | Electronic display element | |
| US3873185A (en) | Variable light-filtering device | |
| US3692388A (en) | Electrically responsive light filter | |
| US3840288A (en) | Electrochromic display having electro-catalyst | |
| GB1566110A (en) | Electrooptical device | |
| US4205903A (en) | Writing/erasing technique for an electrochromic display cell | |
| DE2756769A1 (en) | REVERSIBLE ELECTROCHROMIC DISPLAY DEVICE | |
| CA1059229A (en) | Visual image recording device | |
| US4830471A (en) | Electrochromic material, method of making, and new electrochromic device | |
| US4036551A (en) | Display apparatus | |
| CA1094671A (en) | Visual image display device | |
| Chang et al. | Performance characteristics of electrochromic displays | |
| EP0044392B1 (en) | Electrochromic display device with improved erasing characteristic | |
| US4210909A (en) | Complete bleaching of non-selected display electrodes in an electrochromic display drive | |
| US4837592A (en) | Method of making an electrochromic layer and new electrochromic device made therefrom | |
| CA1038071A (en) | Acid wetted "solid" electrochromic structure | |
| US4844592A (en) | Cathodic electrochromic material, method of making, and new electrochromic device | |
| US4842382A (en) | Electrochromic device, new cathodic electrochromic material and method of making |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |